Biotech has developed a system for labeling DNA fragments with hapten-modified "tails" which can be detected by immunological methods using enzyme-conjugated antibodies. The detection sensitivity of this system is 2-4 picogram, which is sufficient to detect single copy genes in human DNA. The aim of this proposal is to test the applicability of Biotech's system for diagnostic use in clinical laboratories and to produce and market viral diagnostic kits using the derived methodologies. Since DNA hybridization can be up to 1,000 times more sensitive for the diagnosis of viral infections than available immunological techniques, it has the potential for wide application in the clinical diagnostics market. The major drawbacks in using the currently available radioactive probes in clinical laboratories, including high costs, probe instability, exposure hazards, and waste disposal could be eliminated by substituting the nonradioactive probe system described here. Phase I will be used to test the nonradioactive probes for the ability to detect HTLV-III DNA and RNA in cultured human cells. Procedures for extracting and immobilizing the nucleic acids from infected cells, as well as for the hybridization and detection of the DNA probes will be optimized. Simpified protocols suitable for use by clinical labs will then be established. The methodologies developed in Phase I will be further extended to produce, obtain FDA approval, and market diagnostic kits for the detection of HTLV-III using DNA probes. These kits would be valuable for diagnosing patients with AIDS or pre-AIDS, and could be used to screen blood banks prior to use in blood transfusions. The nonradioactive probe technology will eventually be applied to the development of diagnostic kits for other viruses (herpes simplex, cytomegalo virus), cancer diagnosis, and genetic screening. (5)